Central effects of camphor on GnRH and sexual hormones in male rat.

In Persian traditional medicine is believed that camphor (a crystalline ketone obtained from cinnamomum camphora) is a suppressor of sexual behaviors. This study examined the central effects of camphor on sexual hormones (LH, FSH and testosterone) and GnRH plasma levels in male rat. Male Wistar rats weighing 250-260gr were selected and divided into control (no treatment), sham (ICV injection of EtOH 10%) and treatment (ICV injection of camphor in three doses 4, 20, 40 µg/ 10µl in alcohol) groups. The serum samples were used for assaying of GnRH, LH, FSH and testosterone. There were no significant differences in the levels of hormones between the groups of study. Despite the central administration of camphor in hypothalamus - pituitary - gonad (HPG) axis, no significant differences were seen in sex hormone`s levels compared to the control. With this finding, it can be concluded that camphor may not effectively handle the axis via central pathway. These data recommend further studies of camphor on the HPG axis.

amphor (C 10 H 16O ) is a waxy, white crystalline substance or transparent with a solid form and a strong aromatic odor. It is a ketone body from camphor laurel wood (cinnamomum camphora), a large evergreen tree found in Asia (1)(2)(3). It can also be synthetically produced from oil of turpentine. Camphor can be absorbed from skin, GI (5-90 min after ingestion) and respiratory system. It is conjugated in the liver with glucuronic acid to become soluble in water. Camphor crosses the placental barrier it may be account for its embryo toxic effects (5).
Camphor has various applications in different countries especially the Asian countries.
As a form of herbal medicine, it serves as antiseptic, anti-cold (8,9), a synthetic drug in the form of ointments, lotion and gel for anti-insect bites, antimicrobial, embalming, firework, U.V filter cream, topical analgesic, anti-itching, skin cooling, anti-burns and sunburn (10). Also, it is used in plastic retrofitting against solar radiation, pesticides, shining materials, toilet products preservatives, cosmetics, religious ceremonies chewing gum and cigarette (8-10).
Camphor had been administered in cumulative doses to induce convulsion attacks in psychiatric patients (11).
Recent studies showed that organic compound such as camphor reduce cytochrome P 450 B 1 activity. This enzyme interferes with one of the key enzymes in the testosterone synthesis called 17α hydroxilase. By reducing cytochrome, the mentioned enzymes function reduces, so testosterone diminishes (12)(13)(14)(15). Some researchers investigated the impact of camphor in UV -filter ointment on gonadotropins and gonadal hormones and concluded that camphor causes adolescent retardation and reduction in reproductive organs volumes in both sexes (16,17). It has been shown in another study that the use of ointments containing camphor did not affect gonadotropins (LH and FSH) and testosterone (18) and it has also been demonstrated that UV -filters ointment inhibit 17 b -hydroxysteroid dehydrogenase type 3 which catalyzes the last step of testosterone synthesis in testicular leydig cells and plays an essential role during male sexual development (19).
Also, an adverse effect of camphor on rats causing a slight reduction of GnRH, LH and FSH (only in a low dose) was observed in an in vitro study (20). The effect of camphor on estrogenic gene expression (21) and estrogen receptor activity (22) was also studied.
According to Avecina's medicine, camphor is a suppressor of libido and acts as an effective element in reproductive system (23

Surgical procedure
The rats were anesthetized with ketamine (75 mg/kg). For ICV injection, the rats were camphor. The low dilution rate 10% was not a matter of concern. In many reports, alcohol dilution further than 15% affected the reproductive system (25). ICV injection was performed through the cannula implanted on rat brain by the stereotaxic instrument, according to Paxinose Atlas with Hamilton syringe. The blood samples were collected from all animals by orbital sinus blood collection technique (26, 27) and were centrifuged and freezed at-20c. Sera were used for GnRH, LH, FSH and testosterone measurement by rat specific ELISA kit.

Statistical Analysis
Data were analyzed using one way ANOVA followed by Tykey post-hoc test. The difference between data in each point was considered significant at p <0.05.

Results
Serum GnRH and LH levels did not show any significant differences in camphor receiving rats in test group when compared with the control and sham groups. Although some differences were observed, but these differences were not significant (Table 1).

Discussion
As yet, the different results of camphor effects on the reproductive system were reported by several researchers (12)(13)(14)(15)(16)(17)(18)(19). In Iranian folk medicine, camphor is a suppressor of sexual activity (23). In the present study we analyzed the